1. Field of the Invention
The present invention relates to a method of manufacturing a ball joint and, more particularly, to a method of manufacturing a ball joint used in, for instance, a vehicle.
2. Description of the Prior Art
A conventional and typical ball joint which makes two component parts of a vehicle to be swingably joined is illustrated in FIG. 4. A ball joint 100 of this type comprises a socket 102 having a mounting portion 101 at which the socket 102 is fixed to a first component part of the vehicle associated (not shown), a bearing 106 fitted in a recess 108 of the socket 102 and formed with a recess 105 having a configuration complementary with an outer configuration of a ball portion 104 of a ball stud 103 to support the ball portion 104, and a plug 107 retaining the ball portion 104 within the socket 102 via the bearing 106. When the ball portion 104 of the ball stud 103 is rotated while being slided within the recess 105 of the bearing 106, the ball stud 103 which is connected to a second component part (not shown) of the vehicle is allowed to swing relative to the socket 102 in desired directions such as the direction A.
In order to manufacture and assemble such a ball joint 100, a fit-in body is prepared by fitting a ball portion 104 of a ball stud 103 into a recess 105 formed in a flexible and integral bearing 106 with a high level of precision, or an assembled body is prepared by assembling a bearing 106 consisting of at least two components, which together define a recess 105 formed and machined with a high level of precision, around a ball stud 103. Thereafter, the thus prepared fit-in body or assembled body is fit in a recess 108 of a socket 102. Lastly, a plug 107 is fitted in a groove which has previously been formed in the inner peripheral wall of the opening portion of the recess 108 of the socket 102, and the plug 107 is then caulked so as to prevent the fit-in or assembled body from being disengaged from the socket 102.
However, as would be clearly noted from the description given above, the ball joint 100 must have its members, such as the bearing 106, to be formed and machined with high levels of precision. This, together with the relatively large number of component parts required, causes an increase in the number of manufacturing processes required and makes production costs relatively high.
FIG. 5 illustrates another conventional ball joint 115. In the manufacture of the ball joint 115, instead of using the plug 107 to prevent disengagement and loose fit of the bearing 106 and the ball portion 104, the opening edge portion 111 of a socket 110 is caulked so that the ball portion 104 of the ball stud 103 is slidably supported within a recess 114 defined by assembled bearing components 113 and 112 and is retained in place through the flexible bearing portion 112.
However, with the method of manufacturing of the ball joint 115, it is essential to use a bearing member. Because the bearing components 112 and 113 should be formed with a high level of precision and also because relatively large number of components or parts and manufacturing processes are required, production costs become relatively high.